1. Dissolve yeast in warm water. Meanwhile, mix flour and salt, then cut
butter into the flour. Add the dissolved yeast, egg yolks, milk and vanilla.
Mix well—cover and refrigerate for 1 hour.
2. Meanwhile, make Topping: Combine butter, brown sugar and cinnamon until
crumbly in a small bowl. Set aside.
2. Spread mixture in a well-greased 8-inch square pan—spread topping over
cake. Cover and let rise in warm place for 1 hour. Preheat oven to 350 degrees
and bake dough for 35 minutes. Remove and cool.
3. Meanwhile, make Filling: Mix together flour and salt in a saucepan. Stir
in milk—cook, stirring constantly until thickened like paste. Cool. Beat
together butter, sugar and vanilla until light and fluffy—then gradually
beat into the cooled milk mixture. The milk must be cooled completely for
this to work. Mixture should be creamy.
3. Split cake in half to make 2 layers—fill with filling, then replace top
layer of cake.

This sounds like it except I think it will need a different topping. The one we get was usually covered in a very crunchy streusel. Maybe one of the ones with flour in it. Will let you know how it turns out!